i was racing my it200 yesterday, it has been running fine. about 45 minutes in, it started sputtering at all throttle positions. like a very consisitent miss. it will take throttle, and accelerate no problem, it just sputters along the way. doesn't like to idle very well either.. so i thought it was a rich issue - either stuck float, or maybe a broken reed, i completely rebuilt carb, flipped reeds around (they looked good, with no fraying/chunks.) started it back up, and it does the same thing. i then tried running it without the air filter, thinking it was a restriction. still did the same thing. so it's not reed or carb or airfilter.